UPDATE: Liberal interim leader Bob Rae told reporters in Ottawa Wednesday that if Prime Minister Stephen Harper wanted to bring back the measures he would face a “good debate” in Parliament.

“The Prime Minister needs to explain to us why if these measures were so important and necessary they were not in place for four years,” Rae said. “Is the Prime Minister saying that for the last four or five years we were at risk, at greater risk because the measures have not been in place?”

NDP MP Paul Dewar said in an email to Huffington Post Canada on Tuesday that Harper's plan isn't necessary.

“Stephen Harper's plan to reintroduce these draconian provisions simply isn’t backed up by the facts. The government has produced no evidence to justify this move. Security is obviously important to Canadians, and we can make Canada secure without resorting to measures like these.

“In fact, the former Director of CSIS Reid Morden has said that these provisions were needless and crossed the line between state security and individual rights.”

Harper tried to re-introduce the police-broadening powers in 2008, but his efforts failed in 2008 because the Conservative minority government didn’t have the required seat count. Now that Harper has a majority in both chambers, the hurdle he once faced is no longer an obstacle.

The Liberal caucus was divided over the necessity of the measures four years ago, with some MPs who agreed with the governing Tories sitting out the vote.

The Conservative government will reintroduce controversial anti-terrorism measures that were allowed to expire amid privacy concerns and Charter rights complaints, Prime Minister Stephen Harper confirmed to the CBC Tuesday.

On the eve of the 10th anniversary of the 9/11 terrorist attacks, Harper told CBC’s Peter Mansbridge that Canada needs better tools to combat the ongoing threat of major acts of terrorism and Islamist violence.

Among other controversial measures expected to be made law again are preventative arrests and the ability to force individuals to testify at “investigative hearings” if officials suspect they have knowledge of terrorist activity.

“That is our plan (to reintroduce the measures). We think those measures are necessary. We think they've been useful. And as you know, they're applied rarely, but there are times where they're needed,” said Harper in an interview to be broadcast in its entirety Thursday.

The measures were initially included in the Liberal government’s anti-terrorism act passed soon after 9/11 under then prime minister Jean Chrétien. The controversial provisions of the bill were allowed to expire five years later after a majority of Parliamentarians voted not to reinstate them.

The NDP was especially adamant that the measures were a breach of fundamental freedoms and compromised key features of Canada’s justice system and Charter of Rights and Freedoms.

Investigative hearings provide officials with a way to force someone suspected of having information about terrorist activity to testify before a judge. Preventive detention allows the state to incarcerate anyone suspected of involvement in criminal activity without having to prove allegations. Both provisions gave the government far too much power, the NDP argued.

“Not everyone who chooses to remain silent is guilty. People may have very legitimate fears and concerns, such as fears and concerns about their own personal safety,” then NDP MP Bill Siksay told the House of Commons in 2008 when the Tories first tried to reintroduce the measures.

“Jailing people because we think they might do something criminal is very problematic, to say the least,” he added.

But Harper suggested the measures are a rational response to very real threats faced by Canada.

“The major threat is still Islamicism. There are other threats out there, but that is the one that I can tell you occupies the security apparatus most regularly in terms of actual terrorist threats,” Harper said.

“Now, as we've seen in Norway, terrorist threats can come out of the blue. It can come from something completely different, and there are other groups and individuals that if given the chance would engage in terrorism. But that one is probably still the major one,” he noted.

The Prime Minister said Canada not only faces threats from outside its borders, but also from within, in the form of homegrown terrorists.

“When people think of Islamic terrorism, they think of Afghanistan, or maybe they think of someplace in the Middle East, but the truth is that threat exists all over the world. We've seen some recent bombings in Nigeria, domestic Nigerian terrorists,” Harper said, adding “Homegrown is also something that we keep an eye on.”

In its annual report tabled in June, the Canadian Security Intelligence Service (CSIS) noted that the main threat to Canada continues to be Islamist violence.